The invention relates to a drive system for apparatus for automatic culture of biological tissues or cells.
The culture of biological tissues or cells is an essential experimental technique for conducting a microscopic investigation of such medium in every field including the medical science, biology, pharmacy and agricultural science. However, the culture of biological tissues or cells over successive generations involves technical difficulties, which have prevented a stabilized cultured strain from being obtained. However, with the recent development of gas culture in an incubator, namely, culturing in a particular gas atmosphere, the culture over successive generations of cells of special kinds such as liver, neuron, pituitary gland has been made possible through their culturing has been considered difficult in the prior art practice.
The culture over successive generations will be briefly summarized below. A given number of cells are diluted in a culture solution in the form of a suspension, which is injected into a culture vessel such as petri dish. The vessel is placed still in an incubator for culturing of the cells under given gas atmosphere and temperature environment. After a given period of time, the vessel is removed from the incubator and examined for the growth or the increase of the number of cells with the use of a microscope. When it is determined that the intended cells have grown to the full extent of the vessel, it is transferred to a strain-free clean bench, and the culture solution in the vessel is withdrawn with a pipette and disposed. Subsequently, a buffer solution is injected into the vessel to clean the remaining cells. The buffer solution used for the purpose of cleaning is again withdrawn and disposed. The grown cells which attach to the bottom of the vessel are freed therefrom by the injection of an enzyme such as trypsin. The freed cells are separated and collected by using a centrifuge. Thus, the freed cells are separated from the enzyme in the centrifuge, and the decantered solution or enzyme is withdrawn and disposed. The centrifuge may not be used for separating the cells from the enzyme depending on the variety of cells. In this instance, the enzyme is withdrawn and disposed immediately before the cells attaching to the bottom of the vessel are freed by means of the enzyme. Subsequently, a culture solution is injected for distributing the cells in a given diluted concentration, and the cells are again brought into suspension by means of a pipette. The solution containing the cells in suspension is then distributed into fresh culture vessels in given quantities. After such dilution and distribution operations, the vessels are removed from the clean bench and placed still in an incubator which maintains a given environment for allowing the culturing process to proceed.
The conventional technique described above suffers from a number of disadvantages. It will be seen that the examination of the growth of the tissues or cells under the microscope often requires the removal of the culture vessel out of the incubator and into the outer atmosphere. This may cause a sudden change in the culturing conditions such as the gas atmosphere, temperature, humidity or the like, causing a critical influence upon the tissues or cells being cultured. In addition, the exposure to the outer atmosphere may cause a contamination by miscellaneous strains. Thus, the examination brings forth the influence of a change in the environmental conditions and a more direct influence by mixture with miscellaneous strains.
The various operations required for culturing over successive generations rely on a manual operation by an operator in the clean bench. This means that any slight difference in the various operations may have a direct influence upon the culturing result of the tissues or cells. Since the experience and skill of the culturing technique varies from operator to operator, it is difficult to provide a standard procedure for the culturing technique. This makes it impossible to produce the tissues or cells being cultured which are of uniform quality. As a consequence, when different groups of researchers are conducting a common study on the same theme, their conclusions may differ from each other as a result of the difference in the tissues being cultured. In extreme cases, the conclusions may be opposite to each other. This means that the cells or tissues cultured with the conventional technique tended to lack the reliability.
It takes at least two years to train a skilled operator. As a result, there is a continued shortage of such operators, and researchers often have to perform the culturing operation themselves rather than exclusively directing their effort to their study.
In view of these considerations, the present invention is directed towards an automatic culture apparatus capable of performing the described culturing operations automatically in order to eliminate the contamination which may occur as a result of the exposure to the outer atmosphere. Such apparatus also serves to remove the influence of manual operations upon the cultured results and to permit a standard and uniform procedure for the various culturing operations. With this apparatus, the cells which are to be cultured over successive generations are diluted with a culture solution, and a given number of cells are distributed into separate culture vessels to be cultured while they remain at rest. It is necessary that the growth of cells can be observed under a microscope from time to time while the culture is being continued. When the growth has proceeded to a point that a given number of cells are produced, it is necessary to inject an enzyme solution into the vessel to free the cells attaching to the bottom thereof, followed by centrifuging and distributing them into fresh vessels. All of these operations must be automatically performed in a chamber in which a given environment is maintained. To this end, the automatic culture apparatus of the present invention is designed to permit the performance of the described operations and observation, by disposing the observing microscope, distributor and other mechanical devices within the chamber. Then it is necessary to provide a drive system to move a culture vessel containing the cells between various mechanisms or devices which are mounted within the chamber.